Why the East Coast Is Baking

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The U.S. East Coast is sweating through a lingering heat wave
this week. The sweltering heat and humidity have combined to keep
temperatures hot even at night. But relief may finally be in
sight.

Heat
waves are marked by at least three consecutive days of
temperatures of at least 90 degrees Fahrenheit (32 degrees
Celsius). In New York and Boston, temperatures hit 90 degrees F
or hotter Sunday through Wednesday, and are expected to do so
again today (July 18). New York has already reached 96 degrees F
(36 degrees C) by 1 p.m. EDT today. Baltimore reached a record
high of 98 degrees F (37 degrees C) yesterday, the National
Weather Service (NWS) said.

Today and Friday are expected to be the hottest days of the
Northeast's extended heat
wave, according to the NWS' Eastern Region Headquarters.

A giant high-pressure dome in the atmosphere, sitting over the
Ohio Valley, is keeping the East Coast hot and humid. The high
pressure blocks the jet stream's cooler air from reaching the
region and, at the same time, pulls in hot, humid air from the
Gulf of Mexico. The high pressure also keeps the skies clear,
helping to raise temperatures, as can be seen from space in an
image captured by the GOES East satellite.

However, an end is in sight: A cold front will come through
starting Friday, bringing relief first to the Ohio Valley and
Great Lakes and then finally to the Northeast by Sunday, the NWS
said. But the collision between cold and warm air could cause
thunderstorms and heavy rainfall in the Appalachians and the
Carolinas next week, the NWS said.